Fluorinated compounds may be prepared by the gas phase reaction of hydrogen fluoride (HF) with various substrates such as chlorinated compounds. A number of metal oxide-based catalysts have been developed for this purpose. However, such catalysts typically lose activity with prolonged use. Additionally, inactive catalyst precursors often must be activated in order to prepare such fluorination catalysts.
Various methods for activating and reactivating metal oxide-based fluorination catalysts, as well as methods for extending the useful life of such catalysts, have been investigated. However, these methods are known to possess certain disadvantages. For example, oxygen (O2) may be co-fed continuously or intermittently during the fluorination reaction or during reactivation for the purpose of oxidizing and removing carbonaceous deposits, which tend to inhibit catalyst activity, from the catalyst surface. However, water and carbon dioxide typically are produced as by-products. The water generated may itself damage and deactivate the catalyst due to phase changes triggered by the repeated addition and loss of water from the catalyst. The presence of water in the reactor system may also lead to corrosion or erosion of fluorination equipment.
Accordingly, the development of improved, effective procedures for both activating and reactivating catalysts for use in fluorination reactions which avoid the generation of water would be of interest.